It is standard procedure to test integrated circuit (IC) packages which include an IC chip that is resin-sealed to assure that it is an acceptable product. Typically, IC packages are first subjected to an electrical properties test in which the input/output characteristics, pulse characteristics and noise leeway, etc., of the IC chip are tested. Then, those IC packages which have passed the electrical property test are placed in an oven and caused to operate for a certain period of time at a source voltage which is approximately 20 percent higher than the rated value at a relatively high temperature such as 120 degrees centigrade. Those IC packages which fail this burn-in test are dropped as being unsatisfactory and only those IC packages which performed acceptably are shipped out as being satisfactory.
IC packages currently are moving from a terminal insertion type such as the DIP (dual in-line package), etc., to a surface mount type such as a SOP (small outline package), a SOJ (small outline J-leaded package) and a QFP (quad flat package).
FIGS. 13 and 14 show the construction of a socket for the burn-in test according to prior art adapted for loading an IC package 110 of the SOP type.
In this socket, a large number of pin type contacts 102 are arranged at locations corresponding to gull-wing type leads 112 of IC package 110 of the SOP type that is to be loaded on a base 100 of the main socket body. Each contact 102 has a base end 102a which is fixed to base 100, a curved spring part 102b which extends upward in a curved manner in the shape of J from this base end 102a, a contact part 102c which extends vertically upward from the tip of this curved spring part 102b and a connector 102d that protrudes downward through the base 100 from the base end 102a. Additionally, in base 100, a pair of latches 104 and 106b for holding the IC package in place when mounted on the socket are rotatably installed outside both contact rows. Each latch is rotatably biased toward the center of the base by a spring (which is not shown in the drawing).
IC package 110 is loaded onto base 100 while being held on the inner or under side of a carrier 114 whose cross-section is generally in the shape of U. As is shown in FIG. 13, when carrier 114 is inserted with IC package 110, the tapered surface 114a outside the lower part of the carrier 114 contacts the tapered surfaces 104a and 106a inside the tops of the latches 104 and 106 thereby being guided downward by the latches 104 and 106, and causing them to rotate outward in opposition to a spring bias force so that each lead 112 of the IC package 110 is placed atop each corresponding contact 102.
If the carrier 114 is further pushed in opposition to the spring force of the contact 102, the latches 104 and 106 are restored to the original positions as is shown in FIG. 14 with a result that respective upper claw parts 104b and 106b engage with the upper peripheral edge of carrier 114. As a result of the hold-down force on carrier 114 in this state, a reliable electrical contact is obtained between each lead 112 of the IC package 110 and each corresponding contact 102.
FIG. 15 shows the construction of a socket for the burn-in according to prior art for loading IC package 130 of the SOJ type.
In this SOJ socket, a large number of erect type contacts 122 are arranged at locations corresponding to J-shape leads 132 of IC package 130 to be loaded in a base 120 of a main socket body. Each contact 122 arranged in rows has a base end 122a which is fixed to the base 120, a straight-line spring part 122b which extends vertically from the center of this base end 122a, a wide contact part 122c that is formed at the distal end of straight-line spring part 122b, support parts 122d which extends vertically upward from both ends of the base end 122a parallel flanking straight-line spring part 122b and a contact pin 122e that protrudes downward through base 120 from one end of base end 122a. In the base 120, a flange 124 for placing the IC package is provided inside both contact rows.
IC package 130 is inserted into the base 120 without using a carrier with leads 132 facing down as is shown in the drawing. As IC package 130 is mounted on the base, the outer side of each lead 132 slides against the inside end of contact part 122c of each contact 122 with a consequence that the straight-line spring part 122b of each contact 122 is elastically displaced outward. Upon the lower surface of the IC package 130 being placed on the flange 124, a suitable elastic pressure contact and corresponding electric contact are obtained between each lead 132 and contact part 122c of each contact 122.
As illustrated and described above, separate socket having a different construction needs are used for an SOP type IC package and a SOJ IC package. This has been the case even when the SOP and SOJ type packages have the same arrangement pattern for the leads, thus, resulting in higher overall costs. Additionally, in the case of sockets for SOP packages, additional parts such as latches are needed.